System for thermally controlling an electronic display with reduced noise emissions

ABSTRACT

A heat exchanger assembly for an electronic image assembly placed within a housing where ambient air surrounds the exterior of the housing and a rear plate may be placed behind a backlight to create a channel. An ambient air fan may be placed between two portions of a heat exchanger to force ambient air through the heat exchanger. The fan may also be positioned to also force ambient air through the channel. A circulating gas fan may also be placed within the housing to force circulating gas through at least one portion of the heat exchanger.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/211,887 filed on Aug. 17, 2011, now U.S. Pat. No. 8,804,091 issuedAug. 12, 2014. U.S. application Ser. No. 13/211,887 is a non-provisionalapplication of U.S. Provisional Application No. 61/375,470 filed Aug.20, 2010. U.S. application Ser. No. 13/211,887 is also acontinuation-in-part of U.S. application Ser. No. 13/100,580 filed onMay 4, 2011. U.S. application Ser. No. 13/211,887 is also acontinuation-in-part of U.S. application Ser. No. 13/100,556 filed onMay 4, 2011, now U.S. Pat. No. 8,749,749 issued Jun. 10, 2014. U.S.application Ser. No. 13/211,887 is also a continuation-in-part of U.S.application Ser. No. 12/905,704 filed on Oct. 15, 2010, now U.S. Pat.No. 8,773,633 issued Jul. 8, 2014. All aforementioned applications arehereby incorporated by reference in their entirety as if fully citedherein.

TECHNICAL FIELD

Exemplary embodiments generally relate to cooling systems and inparticular to cooling systems for electronic displays.

BACKGROUND OF THE ART

Improvements to electronic displays now allow them to be used in outdoorenvironments for informational, advertising, or entertainment purposes.While displays of the past were primarily designed for operation nearroom temperature, it is now desirable to have displays which are capableof withstanding large surrounding environmental temperature variations.For example, some displays are capable of operating at temperatures aslow as −22 F and as high as 113 F or higher. When surroundingtemperatures rise, the cooling of the internal display components canbecome even more difficult.

Additionally, modern displays have become extremely bright, with somebacklights producing 1,000-2,000 nits or more. Sometimes, theseillumination levels are necessary because the display is being usedoutdoors, or in other relatively bright areas where the displayillumination must compete with other ambient light. In order to producethis level of brightness, illumination devices and electronic displaysmay produce a relatively large amount of heat.

Still further, in some situations radiative heat transfer from the sunthrough a front display surface can also become a source of heat. Insome locations 800-1400 Watts/m² or more through such a front displaysurface is common. Furthermore, the market is demanding larger screensizes for displays. With increased electronic display screen size andcorresponding front display surfaces, more heat will be generated andmore heat will be transmitted into the displays.

Exemplary modern displays have found some effective means for coolingthe displays including circulating a closed loop of gas around thedisplay and drawing ambient gas through the display so that the closedloop of gas may be cooled (as well as portions of the electronicdisplay). Various thermal communications have been discovered which cantransfer heat away from the sensitive electronic components and out ofthe display. Heat exchangers were found to produce an excellent meansfor transferring heat between the closed loop of gas and the ambientgas. However, previous designs for moving the gas through the displayhave been found to generate an undesirable amount of noise emission fromthe display as well as thermal gradients where portions of the displaywere cooled but others remained warm.

When using LCD displays, it was found that backlights were often asource of heat and it was desirable to move gas across the rear surfaceof the backlight in order to cool it. While desirable, it was thoughtthat the front surface of the backlight could not be cooled for fearthat the backlight cavity would become contaminated with dust, dirt, orother particulate.

SUMMARY OF THE EXEMPLARY EMBODIMENTS

Exemplary embodiments may use a combination of circulating gas andambient gas in order to adequately cool an electronic display.Circulating gas may be used to remove heat from the front of the imageassembly. Circulating gas may also be used to remove heat from internalelectronic assemblies. When using a LCD as the electronic imageassembly, circulating gas may also be used to remove heat from thebacklight cavity of the LCD. Because the gas is only circulating withinthe display, it can remain free of particulate and contaminates and willnot harm the display.

Ambient gas may be ingested into the display in order to cool thecirculating gas. The ambient gas and the circulating gas may be drawnthrough a heat exchanger which will allow the heat to transfer from thecirculating gas to the ambient gas, preferably without letting theambient and circulating gases mix with one another. An exemplaryembodiment would use a cross-flow heat exchanger. An additional flow ofambient gas can be drawn across the rear surface of the image assemblyto remove heat from the rear portion of the image assembly. When using aLCD as the electronic image assembly, this additional flow of ambientgas can be used to remove heat from the rear portion of the backlightfor the LCD.

In order to reduce noise emissions, the fans which drive the ambientand/or circulating gas through the heat exchanger may be placed withinthe heat exchanger (or between two separate heat exchangers), which canthen act as a muffler and reduce the noise emitted by the fans. Further,if using the additional ambient gas pathway behind the electronic imageassembly, a manifold may be used to collect the ambient gas along anedge of the display and distribute this into a number of smaller flows.The fans for driving this additional ambient gas pathway can be placedwithin the manifold in order to reduce the noise emitted by the fans andprovide an even distribution of ambient gas across the display. In anexemplary embodiment, a single fan assembly can be used to drive theambient gas through both the heat exchanger(s) and behind the electronicimage assembly.

It has been found that ingesting ambient gas from the top or bottom edgeof the display is preferable as these edges are not typically observableto the viewer. However, when ingesting ambient gas from the top orbottom of a portrait-oriented display, it has been found that as thecool ambient gas travels across the rear portion of the electronic imageassembly and accepts heat it increases in temperature. Once the coolingair reaches the opposite edge (either top or bottom), it may haveincreased in temperature substantially and may no longer provideadequate cooling to the opposing portion of the display. Thus, themanifolds herein allow for cool ambient air to adequately cool theentire electronic image assembly in an even manner and reduce any ‘hotspots’ within the electronic image assembly.

The foregoing and other features and advantages will be apparent fromthe following more detailed description of the particular embodiments ofthe invention, as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of an exemplary embodiment will be obtained froma reading of the following detailed description and the accompanyingdrawings wherein identical reference characters refer to identical partsand in which:

FIG. 1A provides a front perspective view of an exemplary embodiment ofthe electronic display.

FIG. 1B provides a rear perspective view of an exemplary embodiment ofthe electronic display.

FIG. 2 provides a rear perspective view similar to that shown in FIG. 1Bwhere the rear cover has been removed.

FIG. 3 provides a perspective sectional view along the A-A section lineshown in FIG. 1B.

FIG. 4 provides a perspective sectional view along the B-B section lineshown in FIG. 1B.

FIG. 5 provides a perspective sectional view of insert C shown in FIG.4.

FIG. 6 provides a perspective sectional view of one embodiment of thecross through plate.

FIG. 7 provides an exploded perspective view of one embodiment of theheat exchanger.

FIG. 8 provides a perspective sectional view of another embodiment whichuses a flow of circulating gas through the backlight cavity of a liquidcrystal display (LCD).

FIG. 9 provides a perspective sectional view of an exemplary embodimentwhich uses a flow of circulating gas through the backlight cavity inaddition to the flow of circulating gas between the LCD and front plate.

FIG. 10 provides a rear perspective view of an embodiment using a singlefan assembly to control the flow of ambient gas, the embodiment shownwith the rear cover removed.

FIG. 11A provides a perspective sectional view of the embodiment fromFIG. 10 based on section line 11A-11A shown in FIG. 10.

FIG. 11B provides a perspective sectional view of insert B from FIG.11A.

DETAILED DESCRIPTION

The invention is described more fully hereinafter with reference to theaccompanying drawings, in which exemplary embodiments of the inventionare shown. This invention may, however, be embodied in many differentforms and should not be construed as limited to the exemplaryembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. In thedrawings, the size and relative sizes of layers and regions may beexaggerated for clarity.

It will be understood that when an element or layer is referred to asbeing “on” another element or layer, the element or layer can bedirectly on another element or layer or intervening elements or layers.In contrast, when an element is referred to as being “directly on”another element or layer, there are no intervening elements or layerspresent. Like numbers refer to like elements throughout. As used herein,the term “and/or” includes any and all combinations of one or more ofthe associated listed items.

It will be understood that, although the terms first, second, third,etc., may be used herein to describe various elements, components,regions, layers and/or sections, these elements, components, regions,layers and/or sections should not be limited by these terms. These termsare only used to distinguish one element, component, region, layer orsection from another region, layer or section. Thus, a first element,component, region, layer or section discussed below could be termed asecond element, component, region, layer or section without departingfrom the teachings of the present invention.

Spatially relative terms, such as “lower”, “upper” and the like, may beused herein for ease of description to describe the relationship of oneelement or feature to another element(s) or feature(s) as illustrated inthe figures. It will be understood that the spatially relative terms areintended to encompass different orientations of the device in use oroperation, in addition to the orientation depicted in the figures. Forexample, if the device in the figures is turned over, elements describedas “lower” relative to other elements or features would then be oriented“upper” relative the other elements or features. Thus, the exemplaryterm “lower” can encompass both an orientation of above and below. Thedevice may be otherwise oriented (rotated 90 degrees or at otherorientations) and the spatially relative descriptors used hereininterpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Embodiments of the invention are described herein with reference tocross-section illustrations that are schematic illustrations ofidealized embodiments (and intermediate structures) of the invention. Assuch, variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, embodiments of the invention should not be construed aslimited to the particular shapes of regions illustrated herein but areto include deviations in shapes that result, for example, frommanufacturing.

For example, an implanted region illustrated as a rectangle will,typically, have rounded or curved features and/or a gradient of implantconcentration at its edges rather than a binary change from implanted tonon-implanted region. Likewise, a buried region formed by implantationmay result in some implantation in the region between the buried regionand the surface through which the implantation takes place. Thus, theregions illustrated in the figures are schematic in nature and theirshapes are not intended to illustrate the actual shape of a region of adevice and are not intended to limit the scope of the invention.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

FIG. 1A provides a front perspective view of an exemplary embodiment ofthe electronic display 100. A transparent front plate 10 is placed onthe front portion of the display to protect the internal components andallow the images produced by the display 100 to be seen. Someembodiments may use glass as the transparent front plate 10. Exemplaryembodiments may use two pieces of glass laminated with index-matchingoptical adhesive. Some front plates 10 may provide other utility such asanti-reflection or polarizing functions. An inlet aperture 24 and exitaperture 25 may be provided in the housing so that the display 100 canaccept ambient gas for cooling the display 100.

FIG. 1B provides a rear perspective view of an exemplary embodiment ofthe electronic display 100. A rear cover 15 may be used to provideaccess to the internal components of the display 100.

FIG. 2 provides a rear perspective view similar to that shown in FIG. 1Bwhere the rear cover 15 has been removed. Ambient gas 200 may beingested into the display through the inlet aperture 24 and pass througha heat exchanger 45 and exit the display through the exit aperture 25.The ambient gas 200 may be drawn into the display and forced through theheat exchanger 45 using heat exchanger fan assembly 46. An exemplaryplacement for the heat exchanger fan assembly 46 is discussed furtherbelow, but in many embodiments the fan assembly 46 can be placed nearthe inlet aperture 24 and/or exit aperture 25 and may or may not beplaced within the heat exchanger 45 (as shown in FIG. 2).

Optionally, ambient gas 210 may also be ingested into the displaythrough inlet aperture 24. Ambient gas 210 may then be directed througha first manifold 30 which travels along the edge of the display. Thefirst manifold 30 accepts the single larger inlet flow of ambient gas210 and distributes it into a plurality of smaller flows across thedisplay. A second manifold 35 may be placed along the opposite edge ofthe display as the first manifold 30. The second manifold 35 accepts theplurality of smaller flows and combines them into a single flow andexhausts it out of the exit aperture 25. In this embodiment, a manifoldfan assembly 211 is used to draw the ambient gas 210 into the inletaperture 24 and force the ambient gas 210 across the display. For thisparticular embodiment, the manifold fan assembly 211 is placed withinthe first manifold 30 and is used to draw the ambient gas 210 into thedisplay as well as distribute the single flow into a plurality ofsmaller flows. This is not required however, as some embodiments mayplace the manifold fan assembly 211 in the second manifold 35, or withinboth the first and second manifolds 30 and 35.

While both flows of ambient gas may be used in an exemplary embodiment,there is no requirement that they are both used. Some embodiments mayuse only ambient gas 200 or ambient gas 210. Also, if using both flowsof ambient gas 200 and ambient gas 210 there is no requirement that theyshare the same inlet and exit apertures. Thus, there may be separateinlet and exit apertures for the two flows of ambient gas.

FIG. 3 provides a perspective sectional view along the A-A section lineshown in FIG. 1B. Again, ambient gas 200 may be ingested into thedisplay through the inlet aperture 24 and pass through a heat exchanger45 and exit the display through the exit aperture 25. The ambient gas200 may be drawn into the display and forced through the heat exchanger45 using heat exchanger fan assembly 46. Obviously, the inlet aperture24 may contain a filter or other coverings so that contaminates,insects, garbage, and/or water/fluids cannot easily be ingested into thedisplay. However, an exemplary embodiment would not be damaged if theambient gas 200 contained contaminates as they would only pass throughthe heat exchanger 45 which may not be susceptible to damage fromparticulate or contaminates. Exit aperture 25 may also contain some typeof covering to ensure that contaminates and/or insects could not enterthe display.

An electronic image assembly 50 may be placed behind the front plate 10.A plurality of channels 60 may be placed behind (preferably immediatelybehind) the electronic image assembly 50. Ambient gas 210 may be forcedthrough the channels 60 after travelling through the first manifold 30(not shown here). The flow of ambient gas 210 immediately behind theelectronic image assembly 50 may be used to remove any buildup of heatfrom the rear portion of the electronic image assembly 50. It may bepreferable to have a thermally conductive surface on the rear portion ofthe electronic image assembly 50 so that heat can easily transfer tothis plate and be removed by the ambient gas 210.

The channels 60 can take on any number of forms. Although shown in thisembodiment with a square cross-section this is not required. Otherembodiments may contain channels 60 with I-beam cross-sections, hollowsquare cross-sections, hollow rectangular cross-section, solidrectangular or solid square cross-sections, ‘T’ cross-sections, ‘Z’cross-sections, a honeycomb cross-section, or any combination or mixtureof these. The channels 60 are preferably thermally conductive and alsopreferably in thermal communication with the electronic image assembly50. Thus, in a preferred embodiment, heat which accumulates on the rearportion of the electronic image assembly 50 may be transferredthroughout the channels 60 and removed by ambient gas 210.

FIG. 4 provides a perspective sectional view along the B-B section lineshown in FIG. 1B. In this view, the path of the circulating gas 250 canalso be observed. The space between the front plate 10 and theelectronic image assembly 50 may define a front channel 251, throughwhich the circulating gas 250 may travel in order to remove anyaccumulation of heat on the front surface of the electronic imageassembly 50. The circulating gas 250 is preferably then directed intothe heat exchanger 45 where heat may be transferred from the circulatinggas 250 to the ambient gas 200. Upon exiting the heat exchanger 45, thecirculating gas 250 may be re-directed into the front channel 251. Thecirculating gas 250 may also be directed over various electroniccomponents 7 so that heat may be transferred from the electroniccomponents 7 to the circulating gas 250. The electronic components 7could be any one of the following but not limited to: power modules,heat sinks, capacitors, motors, microprocessors, hard drives, AC/DCconverters, transformers, or printed circuit boards.

Also shown in this sectional view is the path of the ambient gas 210travelling down one of the channels 60 directly behind the electronicimage assembly 50. In this embodiment, the ambient gas 210 is forced outof the first manifold 30, across the channels 60, and into the secondmanifold 35 by manifold fan assembly 211. As shown in this Figure, thepaths of the ambient gas 210 and the circulating gas 250 will likelycross, but it is preferable to keep the two gases from mixing (as theambient gas 210 may contain particulate or contaminates while thecirculating gas 250 can remain substantially free of particulate andcontaminates). It may be preferable to keep the circulating gas 250 fromhaving particulate or contaminates because it travels in front of theelectronic image assembly 50. Thus, to keep the image quality from beingimpaired, it may be desirable to keep the circulating gas 250 clean andprevent it from mixing with the ambient gas 210.

FIG. 5 provides a perspective sectional view of insert C shown in FIG.4. As noted above, if practicing an embodiment which uses ambient gas210 as well as the circulating gas 250, the pathways of the two gasesmay need to cross over one another and it may be desirable to prohibitthem from mixing to prevent contamination of sensitive portions of thedisplay. Here, cross through plate 500 allows the pathways of the twogases to cross over one another without letting them mix together. Thecross through plate 500 in this embodiment contains a series of voidswhich pass through the plate. A first series of voids 550 passes throughthe cross through plate 500 and allows ambient gas 210 to travel fromthe first manifold 30 into the channels 60 which run behind theelectronic image assembly 50. A second series of voids 525 pass throughthe cross through plate 500 in a direction substantially perpendicularto that of the first series of voids 550. The second series of voids 525allows the circulating gas to exit the front channel 251, cross over theambient gas 210, and continue towards the heat exchanger 45. In thisembodiment, a circulating gas fan assembly 255 is used to draw thecirculating gas 250 through the front channel 251 and through the heatexchanger 45. Much like the other fan assemblies shown and describedhere, the circulating gas fan assembly 255 could be placed anywherewithin the display, including but not limited to the entrance/exit ofthe heat exchanger 45 or the entrance/exit of the front channel 251.

FIG. 6 provides a perspective sectional view of one embodiment of thecross through plate 500. In this embodiment, the cross through plate 500is comprised of a plurality of hollow blocks 503 sandwiched between atop plate 501 and bottom plate 502 with sections of the plates 501 and502 removed to correspond with the hollow sections of the blocks 503. Aportion of the top plate 501 has been removed to show the detail of thehollow blocks 503, first series of voids 550, and second series of voids525. The cross through plate 500 could take on any number of forms andcould be constructed in a number of ways. Some other embodiments may usea solid plate where the first and second series of voids 550 and 525 arecut out of the solid plate. Other embodiments could use two sets ofhollow blocks where the hollow sections are perpendicular to each otherand the blocks are fastened together. Still other embodiments could usea design similar to those that are taught below for the heat exchanger45, for example any type of cross-flow heat exchanger design could beused.

FIG. 7 provides an exploded perspective view of one embodiment of theheat exchanger 45. In this view, the heat exchanger fan assembly 46 isshown removed from its mounted position within the heat exchanger 45. Inthis embodiment, the heat exchanger 45 is divided into two portions 47and 48 where the fan assembly 46 is placed between the two portions 47and 48. While the fan assembly 46 can be placed anywhere so that itdraws ambient gas 200 through the heat exchanger 45, it has been foundthat placing the fan assembly 46 between the two portions of the heatexchanger can provide a number of benefits. First, the volumetric flowrate of the ambient gas 200 through the heat exchanger is high, whichresults in better cooling capabilities for the heat exchanger 45.Second, the noise produced by the fan assembly 46 can be drasticallyreduced because the surrounding portions 47 and 48 of the heat exchanger45 essentially act as a muffler for the fan assembly 46. In thisembodiment, portion 48 is thinner and longer than portion 47. This wasdone in order to free up more space within the housing so thatadditional electronic components could fit within the housing (adjacentto portion 48). This design may be preferable when it is desirable tocreate the largest possible heat exchanger 45 (for maximum coolingabilities). This is of course not required, and other embodiments mayhave portions which are of equal width and length. Also, although thisembodiment uses the fan assembly 46 to drive the ambient gas 200, otherembodiments could use a fan assembly placed within the heat exchanger todrive the circulating gas 250 instead and drive the ambient gas 200 withanother fan assembly (possibly placed within the heat exchanger orlocated at the entrance/exit of the heat exchanger).

The ambient gas 200 travels through a first pathway (or plurality ofpathways) of the heat exchanger 45 while the circulating gas 250 travelsthrough a second pathway (or plurality of pathways) of the heatexchanger 45. Although not required, it is preferable that thecirculating gas 250 and ambient gas 200 do not mix. This may prevent anycontaminates and/or particulate that is present within the ambient gas200 from harming the interior of the display. In a preferred embodiment,the heat exchanger 45 would be a cross-flow heat exchanger. However,many types of heat exchangers are known and can be used with any of theembodiments herein. The heat exchanger 45 may be a cross-flow, parallelflow, or counter-flow heat exchanger. In an exemplary embodiment, theheat exchanger 45 would be comprised of a plurality of stacked layers ofthin plates. The plates may have a corrugated, honeycomb, or tubulardesign, where a plurality of channels/pathways/tubes travel down theplate length-wise. The plates may be stacked such that the directions ofthe pathways are alternated with each adjacent plate, so that eachplate's pathways are substantially perpendicular to the pathways of theadjacent plates. Thus, ambient gas or circulating gas may enter anexemplary heat exchanger only through plates whose channels or pathwaystravel parallel to the path of the gas. Because the plates arealternated, the circulating gas and ambient gas may travel in plateswhich are adjacent to one another and heat may be transferred betweenthe two gases without mixing the gases themselves (if the heat exchangeris adequately sealed, which is preferable but not required). In otherwords, an exemplary heat exchanger would have at least a first gaspathway for ambient gas and at least a second gas pathway forcirculating gas, where the two pathways are substantially perpendicularand adjacent to each other and do not allow the ambient gas andcirculating gas to mix.

In an alternative design for a heat exchanger, an open channel may beplaced in between a pair of corrugated, honeycomb, or tubular plates.The open channel may travel in a direction which is perpendicular to thepathways of the adjacent plates. This open channel may be created byrunning two strips of material or tape (esp. very high bond (VHB) tape)between two opposite edges of the plates in a direction that isperpendicular to the direction of the pathways in the adjacent plates.Thus, gas entering the heat exchanger in a first direction may travelthrough the open channel (parallel to the strips or tape). Gas which isentering in a second direction (substantially perpendicular to the firstdirection) would travel through the pathways of the adjacent plates).

Other types of cross-flow heat exchangers could include a plurality oftubes which contain the first gas and travel perpendicular to the pathof the second gas. As the second gas flows over the tubes containing thefirst gas, heat is exchanged between the two gases. Obviously, there aremany types of cross-flow heat exchangers and any type would work withthe embodiments herein.

An exemplary heat exchanger may have plates where the sidewalls have arelatively low thermal resistance so that heat can easily be exchangedbetween the two gases. A number of materials can be used to create theheat exchanger. Preferably, the material used should be corrosionresistant, rot resistant, light weight, and inexpensive. Metals aretypically used for heat exchangers because of their high thermalconductivity and would work with these embodiments. However, it has beendiscovered that plastics and composites can also satisfy the thermalconditions for electronic displays. An exemplary embodiment wouldutilize polypropylene as the material for constructing the plates forthe heat exchanger. It has been found that although polypropylene mayseem like a poor thermal conductor, the large amount of surface arearelative to a small sidewall thickness, results in an overall thermalresistance that is low. Thus, an exemplary heat exchanger would be madeof plastic and would thus produce a display assembly that is thin andlightweight. Specifically, corrugated plastic may be used for each platelayer where they are stacked together in alternating fashion (i.e. eachadjacent plate has channels which travel in a direction perpendicular tothe surrounding plates).

FIG. 8 provides a perspective sectional view of another embodiment whichuses a flow of circulating gas 350 through the backlight cavity of aliquid crystal display (LCD) 300. In this embodiment, a LCD 300 and anassociated backlight 320 are used as the electronic image assembly. Abacklight wall 330 may be placed between the LCD 300 and the backlight320 in order to enclose the area and create a backlight cavity.Typically, the backlight cavity is closed to preventcontaminates/particulate from entering the backlight cavity anddisrupting the optical/electrical functions of the backlight 320.However, as discussed above the exemplary embodiments may use a cleangaseous matter for the circulating gases which could now be used toventilate the backlight cavity in order to cool the backlight 320 andeven the rear portion of the LCD 300. An opening 340 can be placed inthe backlight wall 330 to allow circulating gas 350 to flow through thebacklight cavity. A fan assembly 360 may be used to draw the circulatinggas 350 through the backlight cavity. In an exemplary embodiment therewould be an opening on the opposing backlight wall (on the opposite sideof the display as shown in this figure) so that circulating gas 350could easily flow through the backlight cavity.

FIG. 9 provides a perspective sectional view of an exemplary embodimentwhich uses a flow of circulating gas 350 through the backlight cavity inaddition to the flow of circulating gas 250 between the LCD 300 andfront plate 10. Circulating gas fan assembly 255 may be placed so thatit can draw circulating gas 350 through the backlight cavity as well ascirculating gas 250 between the LCD 300 and the front plate 10. Asdiscussed above, the circulating gases 250 and 350 are preferably forcedthrough the heat exchanger 45 (not shown in this figure) so that theymay be cooled by the ambient gas 200 (also not shown in this figure).

Also shown in FIG. 9 is the optional additional flow of ambient gas 210which may travel immediately behind the backlight 320. Once travellingthrough the first manifold 30, the ambient gas 210 may pass through thechannels 60 in order to remove heat from the backlight 320 and even thechannels 60 themselves (if they are thermally conductive). The manifoldfan assembly 211 may be used to draw the ambient gas 210 into the firstmanifold 30 and through the channels 60. Again, the cross though plate500 may be used to allow the circulating gases 350 and 250 to crosspaths with the ambient gas 210 without letting the two gases mix.

In an exemplary embodiment, the backlight 320 would contain a pluralityof LEDs mounted on a thermally conductive substrate (preferably a metalcore PCB). On the surface of the thermally conductive substrate whichfaces the channels 60 there may be a thermally conductive front platewhich may be in thermal communication with the channels 60. In anexemplary embodiment, the thermally conductive plate would be metallicand more preferably aluminum.

FIG. 10 provides a rear perspective view of an embodiment 1000 using asingle fan assembly 1050 to control the flow of ambient gas. Theembodiment 1000 is shown here with the rear cover removed. In thisfigure, the main display assembly is still within the exterior displayhousing 1001. Similar to some of the embodiments describe above, acirculating gas fan assembly 1105 may be used to draw circulating gas1106 into and through the heat exchanger 1100. Further, anothercirculating gas fan assembly 1205 may be used to draw circulating gas1106 through heat exchanger 1200. The circulating gas 1106 may also beused to extract heat from various electrical components 1109.

An ambient gas fan assembly 1050 may be used to draw ambient gas intothe inlet aperture 1009 and exhaust the ambient gas out of an exitaperture 1010. The ambient gas preferably travels through the heatexchangers 1200 and 1100 as well as the channel behind the electronicimage assembly (if used). The section line 11A-11A is shown cuttinghorizontally through the display embodiment 1000.

FIG. 11A provides a perspective sectional view of the embodiment fromFIG. 10 based on section line 11A-11A shown in FIG. 10. For clarity, theexterior housing 1001 has been removed. Once the circulating gas 1106has traveled through the heat exchangers 1200 and 1100, it may then bedirected between the front transparent plate 1500 and the electronicimage assembly 1600. After passing between the front transparent plate1500 and the electronic image assembly 1600, the circulating gas 1106may then return to the heat exchangers 1200 and 1100. In thisembodiment, fan assembly 1050 is used to control the flow of ambient gas1055 and 1056. Ambient gas 1055 is directed through the heat exchangers1200 and 1100 while ambient gas 1056 is directed behind the electronicimage assembly 1600.

FIG. 11B provides a perspective sectional view of insert B from FIG.11A. The channel 1700 may be defined by the space between the rearsurface or portion of the electronic image assembly 1600 and a platewhich is substantially parallel to the rear surface or portion of theelectronic image assembly 1600. The channel 1700 may also contain ribswhich are also thermally conductive and preferably in thermalcommunication with the electronic image assembly 1600. By placing thefan assembly 1050 so as to direct the ambient gas within the channel1700 and the heat exchangers 1200 and 1100 simultaneously, severalimprovements can be achieved, including but not limited to: increasedair flow, less fan noise, and a less expensive/lighter assembly. In thisembodiment, the paths for ambient gas 1055 and ambient gas 1056 aresubstantially parallel to one another.

As noted above, many electronic image assemblies (especially LEDs, LCDs,and OLEDs) may have performance properties which vary depending ontemperature. When ‘hot spots’ are present within an image assembly,these hot spots can result in irregularities in the resulting imagewhich might be visible to the end user. Thus, with the embodimentsdescribed herein, the heat which may be generated by the image assembly(sometimes containing a backlight assembly) can be distributed (somewhatevenly) throughout the channels 60 and thermally-conductive surfaces toremove hot spots and cool the backlight and/or electronic imageassembly.

The circulating gases and ambient gases can be any number of gaseousmatters. In some embodiments, air may be used as the gas for all.Preferably, because the circulating gases may travel in front of theimage assembly and/or within the backlight cavity, they should besubstantially clear, so that they will not affect the appearance of theimage to a viewer. The circulating gases should also preferably besubstantially free of contaminates and/or particulate (ex. dust, dirt,pollen, water vapor, smoke, etc.) in order to prevent an adverse effecton the image quality and/or damage to the internal electroniccomponents. It may sometimes be preferable to keep ambient gases fromhaving contaminates as well. Filters may be used to help reduce theparticulate within ambient gases. Filters could be placed near the inletapertures so that ambient gases could be drawn through the filter.However, in an exemplary embodiment the display may be designed so thatcontaminates could be present within the ambient gases but this will notharm the display. In these embodiments, the heat exchanger, manifolds,channels, and any other pathway for ambient or circulating gas should beproperly sealed so that any contaminates in the ambient gas would notenter sensitive portions of the display. Thus, in these exemplaryembodiments, ingesting ambient air for the ambient gases, even if theambient air contains contaminates, will not harm the display. This canbe particularly beneficial when the display is used in outdoorenvironments or indoor environments where contaminates are present inthe ambient air.

The cooling system may run continuously. However, if desired,temperature sensing devices (not shown) may be incorporated within theelectronic display to detect when temperatures have reached apredetermined threshold value. In such a case, the various cooling fansmay be selectively engaged when the temperature in the display reaches apredetermined value. Predetermined thresholds may be selected and thesystem may be configured to advantageously keep the display within anacceptable temperature range. Typical thermostat assemblies can be usedto accomplish this task. Thermocouples may be used as the temperaturesensing devices.

It is to be understood that the spirit and scope of the disclosedembodiments provides for the cooling of many types of displays. By wayof example and not by way of limitation, embodiments may be used inconjunction with any of the following electronic image assemblies: LCD(all types), light emitting diode (LED), organic light emitting diode(OLED), field emitting display (FED), light emitting polymer (LEP),organic electro luminescence (OEL), plasma displays, and any other thinpanel electronic image assembly. Furthermore, embodiments may be usedwith displays of other types including those not yet discovered. Inparticular, it is contemplated that the system may be well suited foruse with full color, flat panel OLED displays. Exemplary embodiments mayalso utilize large (55 inches or more) LED backlit, high definitionliquid crystal displays (LCD). While the embodiments described hereinare well suited for outdoor environments, they may also be appropriatefor indoor applications (e.g., factory/industrial environments, spas,locker rooms) where thermal stability of the display may be at risk.

As is well known in the art, electronic displays can be oriented in aportrait manner or landscape manner and either can be used with theembodiments herein. Although circulating gas may be shown travelingclockwise or counterclockwise, either orientation may be used with anyof the embodiments herein. Similarly, although ambient gas may be showntravelling from top-bottom, bottom-top, left-right, or right-left, anyarrangement can be used. Further, it should be understood that thefigures herein are not necessarily drawn to scale, and some componentsmay be enlarged for clarity and explanatory purposes.

Having shown and described preferred embodiments, those skilled in theart will realize that many variations and modifications may be made toaffect the described embodiments and still be within the scope of theclaimed invention. Additionally, many of the elements indicated abovemay be altered or replaced by different elements which will provide thesame result and fall within the spirit of the claimed invention. It isthe intention, therefore, to limit the invention only as indicated bythe scope of the claims.

1. A heat exchanger assembly for use with an electronic image assemblywithin a housing where ambient air surrounds the exterior of thehousing, the assembly comprising: a first portion of a heat exchangercomprising a plurality of stacked plates where each plate contains aplurality of parallel channels; a second portion of a heat exchangercomprising a plurality of stacked plates where each plate contains aplurality of parallel channels; and a fan positioned between the firstand second portions.
 2. The heat exchanger assembly of claim 1 wherein:the fan draws ambient air into the housing.
 3. The heat exchangerassembly of claim 1 wherein: the fan exhausts ambient air out of thehousing.
 4. The heat exchanger assembly of claim 1 wherein: the channelswithin the first portion of the heat exchanger are in gaseouscommunication with the channels within the second portion of the heatexchanger.
 5. The heat exchanger assembly of claim 1 wherein: the twoportions of the heat exchanger are sealed to prevent ambient air fromentering the interior of the housing, other than the pathways within theheat exchanger.
 6. The heat exchanger assembly of claim 1 wherein: theheat exchanger portions are comprised of corrugated layers.
 7. The heatexchanger assembly of claim 1 wherein: the heat exchanger portions arecross-flow heat exchanger portions.
 8. A heat exchanger assembly for usewith an electronic image assembly within a housing where ambient airsurrounds the exterior of the housing, the assembly comprising: a firstportion of a heat exchanger comprising X stacked plates where each platecontains a plurality of parallel channels; a second portion of a heatexchanger comprising Y stacked plates where each plate contains aplurality of parallel channels; and a fan positioned between the firstand second portions; wherein X and Y are not equal.
 9. The heatexchanger assembly of claim 8 wherein: the fan draws ambient air intothe housing.
 10. The heat exchanger assembly of claim 8 wherein: the fanexhausts ambient air out of the housing.
 11. The heat exchanger assemblyof claim 8 wherein: the channels within the first portion of the heatexchanger are in gaseous communication with the channels within thesecond portion of the heat exchanger.
 12. The heat exchanger assembly ofclaim 8 wherein: the two portions of the heat exchanger are sealed toprevent ambient air from entering the interior of the housing, otherthan the pathways within the heat exchanger.
 13. The heat exchangerassembly of claim 8 wherein: the heat exchanger portions are comprisedof corrugated layers.
 14. The heat exchanger assembly of claim 8wherein: the heat exchanger portions are cross-flow heat exchangerportions.
 15. A heat exchanger assembly for use with an electronic imageassembly placed within a housing where ambient air surrounds theexterior of the housing and a rear plate is placed behind a backlight tocreate a channel, the assembly comprising: a first portion of a heatexchanger; a second portion of a heat exchanger; and an ambient air fanpositioned between the first and second portions so as to draw ambientair through the first and second portions of the heat exchanger as wellas through the channel.
 16. The heat exchanger assembly of claim 15further comprising: a circulating gas fan positioned to force a closedloop of circulating gas through at least one portion of the heatexchanger.
 17. The heat exchanger assembly of claim 16 furthercomprising: a plurality of ribs placed within the channel.
 18. The heatexchanger assembly of claim 16 further comprising: a power module placedwithin the path of the circulating gas.
 19. The heat exchanger assemblyof claim 17 wherein: the heat exchanger is a cross-flow heat exchangercomprised of corrugated layers.
 20. The heat exchanger assembly of claim17 wherein: the ribs are metallic.